Obesity is a serious health-related disorder. It has been linked as an important factor for risk of cardiovascular disease, high blood pressure, cancer, and serum cholesterol levels. Further, obesity is very resistant to treatment and it often begins in childhood and tracks over time. While behavioral approaches to prevention of obesity in children is an obvious goal, the literature to date suggests that adequate treatment strategies based on informed empirical data are premature. Studies are needed both to pinpoint behavioral targets for intervention and to identify psychosocial risk factors so that obesity can be prevented safely, economically, and efficiently in children. Thus, we propose to develop behavioral/observational assessments that will carefully assess food intake, physical activity, and parental influences on children's food intake and physical activity. We will also assess the relationship between food intake, physical activity, and parental influences on children's energy balance behaviors in a prospective, longitudinal study. The present study is conceptualized as a multi-stage, multi-method design, consistent with generalizibility theory, and incorporating the following facets: Subjects (N=60), by Observers (1 versus 2), by Occasions (Retests at 1,3,6,12 months) and by level of reactivity (1 versus 2 observers; 1 versus 2 days of assessment). Subjects will be observed all day in the natural environment utilizing direct observation. We will carefully assess food intake, type of food ingested, and parent-child interactions related to food intake and physical activity. Dietary recall and anthropomorphic data will also be collected at each observation. Subjects will be observed one month, three months, six months, and one year later to assess the temporal stability of our measures. The outcomes of the present study will have important implications for future research. A logical next step will be to assess the early natural history of obesity at birth and to follow these children longitudinally throughout childhood. The eventual goal of these series of studies is to pinpoint empirically based intervention targets so that obesity can be prevented safely and economically.